I was speaking to one of the more famous watchmakers the other day about a customer who's brand new watch has become magnetized.

He mentioned that over the last few years, there's been a huge uptick in watches coming in to him that are magnetized, and he figured out that in most cases it has to do with the customer having an induction cooktop.

From the very scientific webpage explainthatstuff.com, you can read the article by clicking HERE.

Induction hobs run at frequencies of over 20KHz (as indicated in the OP/linked article) -- the chance of them actually magnetising anything is small to non existent. If they were any good at magnetising things then I'd have been able to skip buying hooks to hang pans from and would have simply stuck them to the fridge or cooker hood or something - they'd all be nicely magnetised.

Now, watch demagnetisers kind of work the same way as induction hobs -- alternating magnetic fields reducing in amplitude. You can do the reducing in amplitude bit electrically by reducing field strength or you can just move the watch out of the field, inverse square and all that. Permanent magnets (non alternating) are a danger but alternating magnets at IH frequency aren't worth bothering about.

I've got an induction hob and a pile of mechanical watches, I use both a lot and use them together -- no problems. I've also got a pile of pans that are annoyingly rattling about on hooks rather than being nicely stuck to the cooker hood or fridge.